onstitution, habits, voice, colouring, and in most parts of their
structure, with the wild rock-pigeon, yet are certainly highly abnormal in
other parts of their structure; we may look in vain throughout the whole
great family of Columbidae for a beak like that of the English carrier, or
that of the short-faced tumbler, or barb; for reversed feathers like those
of the Jacobin; for a crop like that of the pouter; for tail-feathers like
those of the fantail. Hence it must be assumed not only that half-civilized
man succeeded in thoroughly domesticating several species, but that he
intentionally or by chance picked out extraordinarily abnormal species; and
further, that these very species have since all become extinct or unknown.
So many strange contingencies seem to me improbable in the highest degree.
{25}

Some facts in regard to the colouring of pigeons well deserve
consideration. The rock-pigeon is of a slaty-blue, and has a white rump
(the Indian subspecies, C. intermedia of Strickland, having it bluish); the
tail has a terminal dark bar, with the bases of the outer feathers
externally edged with white; the wings have two black bars; some
semi-domestic breeds and some apparently truly wild breeds have, besides
the two black bars, the wings chequered with black. These several marks do
not occur together in any other species of the whole family. Now, in every
one of the domestic breeds, taking thoroughly well-bred birds, all the
above marks, even to the white edging of the outer tail-feathers, sometimes
concur perfectly developed. Moreover, when two birds belonging to two
distinct breeds are crossed, neither of which is blue or has any of the
above-specified marks, the mongrel offspring are very apt suddenly to
acquire these characters; for instance, I crossed some uniformly white
fantails with some uniformly black barbs, and they produced mottled brown
and black birds; these I again crossed together, and one grandchild of the
pure white fantail and pure black barb was of as beautiful a blue colour,
with the white rump, double black wing-bar, and barred and white-edged
tail-feathers, as any wild rock-pigeon! We can understand these facts, on
the well-known principle of reversion to ancestral characters, if all the
domestic breeds have descended from the rock-pigeon. But if we deny this,
we must make one of the two following highly improbable suppositions.
Either, firstly, that all the several imagined aboriginal stocks w